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diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt new file mode 100644 index 00000000..2bc65f78 --- /dev/null +++ b/Documentation/kernel-parameters.txt @@ -0,0 +1,2661 @@ + Kernel Parameters + ~~~~~~~~~~~~~~~~~ + +The following is a consolidated list of the kernel parameters as implemented +(mostly) by the __setup() macro and sorted into English Dictionary order +(defined as ignoring all punctuation and sorting digits before letters in a +case insensitive manner), and with descriptions where known. + +Module parameters for loadable modules are specified only as the +parameter name with optional '=' and value as appropriate, such as: + + modprobe usbcore blinkenlights=1 + +Module parameters for modules that are built into the kernel image +are specified on the kernel command line with the module name plus +'.' plus parameter name, with '=' and value if appropriate, such as: + + usbcore.blinkenlights=1 + +Hyphens (dashes) and underscores are equivalent in parameter names, so + log_buf_len=1M print-fatal-signals=1 +can also be entered as + log-buf-len=1M print_fatal_signals=1 + + +This document may not be entirely up to date and comprehensive. The command +"modinfo -p ${modulename}" shows a current list of all parameters of a loadable +module. Loadable modules, after being loaded into the running kernel, also +reveal their parameters in /sys/module/${modulename}/parameters/. Some of these +parameters may be changed at runtime by the command +"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}". + +The parameters listed below are only valid if certain kernel build options were +enabled and if respective hardware is present. The text in square brackets at +the beginning of each description states the restrictions within which a +parameter is applicable: + + ACPI ACPI support is enabled. + AGP AGP (Accelerated Graphics Port) is enabled. + ALSA ALSA sound support is enabled. + APIC APIC support is enabled. + APM Advanced Power Management support is enabled. + AVR32 AVR32 architecture is enabled. + AX25 Appropriate AX.25 support is enabled. + BLACKFIN Blackfin architecture is enabled. + CMA Contiguous Memory Allocator is enabled. + DRM Direct Rendering Management support is enabled. + EDD BIOS Enhanced Disk Drive Services (EDD) is enabled + EFI EFI Partitioning (GPT) is enabled + EIDE EIDE/ATAPI support is enabled. + FB The frame buffer device is enabled. + GCOV GCOV profiling is enabled. + HW Appropriate hardware is enabled. + IA-64 IA-64 architecture is enabled. + IMA Integrity measurement architecture is enabled. + IOSCHED More than one I/O scheduler is enabled. + IP_PNP IP DHCP, BOOTP, or RARP is enabled. + IPV6 IPv6 support is enabled. + ISAPNP ISA PnP code is enabled. + ISDN Appropriate ISDN support is enabled. + JOY Appropriate joystick support is enabled. + KGDB Kernel debugger support is enabled. + KVM Kernel Virtual Machine support is enabled. + LIBATA Libata driver is enabled + LP Printer support is enabled. + LOOP Loopback device support is enabled. + M68k M68k architecture is enabled. + These options have more detailed description inside of + Documentation/m68k/kernel-options.txt. + MCA MCA bus support is enabled. + MDA MDA console support is enabled. + MOUSE Appropriate mouse support is enabled. + MSI Message Signaled Interrupts (PCI). + MTD MTD (Memory Technology Device) support is enabled. + NET Appropriate network support is enabled. + NUMA NUMA support is enabled. + NFS Appropriate NFS support is enabled. + OSS OSS sound support is enabled. + PV_OPS A paravirtualized kernel is enabled. + PARIDE The ParIDE (parallel port IDE) subsystem is enabled. + PARISC The PA-RISC architecture is enabled. + PCI PCI bus support is enabled. + PCIE PCI Express support is enabled. + PCMCIA The PCMCIA subsystem is enabled. + PNP Plug & Play support is enabled. + PPC PowerPC architecture is enabled. + PPT Parallel port support is enabled. + PS2 Appropriate PS/2 support is enabled. + RAM RAM disk support is enabled. + S390 S390 architecture is enabled. + SCSI Appropriate SCSI support is enabled. + A lot of drivers have their options described inside + the Documentation/scsi/ sub-directory. + SECURITY Different security models are enabled. + SELINUX SELinux support is enabled. + APPARMOR AppArmor support is enabled. + SERIAL Serial support is enabled. + SH SuperH architecture is enabled. + SMP The kernel is an SMP kernel. + SPARC Sparc architecture is enabled. + SWSUSP Software suspend (hibernation) is enabled. + SUSPEND System suspend states are enabled. + FTRACE Function tracing enabled. + TPM TPM drivers are enabled. + TS Appropriate touchscreen support is enabled. + UMS USB Mass Storage support is enabled. + USB USB support is enabled. + USBHID USB Human Interface Device support is enabled. + V4L Video For Linux support is enabled. + VGA The VGA console has been enabled. + VT Virtual terminal support is enabled. + WDT Watchdog support is enabled. + XT IBM PC/XT MFM hard disk support is enabled. + X86-32 X86-32, aka i386 architecture is enabled. + X86-64 X86-64 architecture is enabled. + More X86-64 boot options can be found in + Documentation/x86/x86_64/boot-options.txt . + X86 Either 32bit or 64bit x86 (same as X86-32+X86-64) + XEN Xen support is enabled + +In addition, the following text indicates that the option: + + BUGS= Relates to possible processor bugs on the said processor. + KNL Is a kernel start-up parameter. + BOOT Is a boot loader parameter. + +Parameters denoted with BOOT are actually interpreted by the boot +loader, and have no meaning to the kernel directly. +Do not modify the syntax of boot loader parameters without extreme +need or coordination with <Documentation/x86/boot.txt>. + +There are also arch-specific kernel-parameters not documented here. +See for example <Documentation/x86/x86_64/boot-options.txt>. + +Note that ALL kernel parameters listed below are CASE SENSITIVE, and that +a trailing = on the name of any parameter states that that parameter will +be entered as an environment variable, whereas its absence indicates that +it will appear as a kernel argument readable via /proc/cmdline by programs +running once the system is up. + +The number of kernel parameters is not limited, but the length of the +complete command line (parameters including spaces etc.) is limited to +a fixed number of characters. This limit depends on the architecture +and is between 256 and 4096 characters. It is defined in the file +./include/asm/setup.h as COMMAND_LINE_SIZE. + + + acpi= [HW,ACPI,X86] + Advanced Configuration and Power Interface + Format: { force | off | strict | noirq | rsdt } + force -- enable ACPI if default was off + off -- disable ACPI if default was on + noirq -- do not use ACPI for IRQ routing + strict -- Be less tolerant of platforms that are not + strictly ACPI specification compliant. + rsdt -- prefer RSDT over (default) XSDT + copy_dsdt -- copy DSDT to memory + + See also Documentation/power/pm.txt, pci=noacpi + + acpi_apic_instance= [ACPI, IOAPIC] + Format: <int> + 2: use 2nd APIC table, if available + 1,0: use 1st APIC table + default: 0 + + acpi_backlight= [HW,ACPI] + acpi_backlight=vendor + acpi_backlight=video + If set to vendor, prefer vendor specific driver + (e.g. thinkpad_acpi, sony_acpi, etc.) instead + of the ACPI video.ko driver. + + acpi.debug_layer= [HW,ACPI,ACPI_DEBUG] + acpi.debug_level= [HW,ACPI,ACPI_DEBUG] + Format: <int> + CONFIG_ACPI_DEBUG must be enabled to produce any ACPI + debug output. Bits in debug_layer correspond to a + _COMPONENT in an ACPI source file, e.g., + #define _COMPONENT ACPI_PCI_COMPONENT + Bits in debug_level correspond to a level in + ACPI_DEBUG_PRINT statements, e.g., + ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... + The debug_level mask defaults to "info". See + Documentation/acpi/debug.txt for more information about + debug layers and levels. + + Enable processor driver info messages: + acpi.debug_layer=0x20000000 + Enable PCI/PCI interrupt routing info messages: + acpi.debug_layer=0x400000 + Enable AML "Debug" output, i.e., stores to the Debug + object while interpreting AML: + acpi.debug_layer=0xffffffff acpi.debug_level=0x2 + Enable all messages related to ACPI hardware: + acpi.debug_layer=0x2 acpi.debug_level=0xffffffff + + Some values produce so much output that the system is + unusable. The "log_buf_len" parameter may be useful + if you need to capture more output. + + acpi_display_output= [HW,ACPI] + acpi_display_output=vendor + acpi_display_output=video + See above. + + acpi_irq_balance [HW,ACPI] + ACPI will balance active IRQs + default in APIC mode + + acpi_irq_nobalance [HW,ACPI] + ACPI will not move active IRQs (default) + default in PIC mode + + acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA + Format: <irq>,<irq>... + + acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for + use by PCI + Format: <irq>,<irq>... + + acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT + + acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS + Format: To spoof as Windows 98: ="Microsoft Windows" + + acpi_osi= [HW,ACPI] Modify list of supported OS interface strings + acpi_osi="string1" # add string1 -- only one string + acpi_osi="!string2" # remove built-in string2 + acpi_osi= # disable all strings + + acpi_pm_good [X86] + Override the pmtimer bug detection: force the kernel + to assume that this machine's pmtimer latches its value + and always returns good values. + + acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode + Format: { level | edge | high | low } + + acpi_serialize [HW,ACPI] force serialization of AML methods + + acpi_skip_timer_override [HW,ACPI] + Recognize and ignore IRQ0/pin2 Interrupt Override. + For broken nForce2 BIOS resulting in XT-PIC timer. + + acpi_sleep= [HW,ACPI] Sleep options + Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, + old_ordering, s4_nonvs, sci_force_enable } + See Documentation/power/video.txt for information on + s3_bios and s3_mode. + s3_beep is for debugging; it makes the PC's speaker beep + as soon as the kernel's real-mode entry point is called. + s4_nohwsig prevents ACPI hardware signature from being + used during resume from hibernation. + old_ordering causes the ACPI 1.0 ordering of the _PTS + control method, with respect to putting devices into + low power states, to be enforced (the ACPI 2.0 ordering + of _PTS is used by default). + nonvs prevents the kernel from saving/restoring the + ACPI NVS memory during suspend/hibernation and resume. + sci_force_enable causes the kernel to set SCI_EN directly + on resume from S1/S3 (which is against the ACPI spec, + but some broken systems don't work without it). + + acpi_use_timer_override [HW,ACPI] + Use timer override. For some broken Nvidia NF5 boards + that require a timer override, but don't have HPET + + acpi_enforce_resources= [ACPI] + { strict | lax | no } + Check for resource conflicts between native drivers + and ACPI OperationRegions (SystemIO and SystemMemory + only). IO ports and memory declared in ACPI might be + used by the ACPI subsystem in arbitrary AML code and + can interfere with legacy drivers. + strict (default): access to resources claimed by ACPI + is denied; legacy drivers trying to access reserved + resources will fail to bind to device using them. + lax: access to resources claimed by ACPI is allowed; + legacy drivers trying to access reserved resources + will bind successfully but a warning message is logged. + no: ACPI OperationRegions are not marked as reserved, + no further checks are performed. + + add_efi_memmap [EFI; X86] Include EFI memory map in + kernel's map of available physical RAM. + + agp= [AGP] + { off | try_unsupported } + off: disable AGP support + try_unsupported: try to drive unsupported chipsets + (may crash computer or cause data corruption) + + ALSA [HW,ALSA] + See Documentation/sound/alsa/alsa-parameters.txt + + alignment= [KNL,ARM] + Allow the default userspace alignment fault handler + behaviour to be specified. Bit 0 enables warnings, + bit 1 enables fixups, and bit 2 sends a segfault. + + amd_iommu= [HW,X86-84] + Pass parameters to the AMD IOMMU driver in the system. + Possible values are: + fullflush - enable flushing of IO/TLB entries when + they are unmapped. Otherwise they are + flushed before they will be reused, which + is a lot of faster + off - do not initialize any AMD IOMMU found in + the system + + amijoy.map= [HW,JOY] Amiga joystick support + Map of devices attached to JOY0DAT and JOY1DAT + Format: <a>,<b> + See also Documentation/kernel/input/joystick.txt + + analog.map= [HW,JOY] Analog joystick and gamepad support + Specifies type or capabilities of an analog joystick + connected to one of 16 gameports + Format: <type1>,<type2>,..<type16> + + apc= [HW,SPARC] + Power management functions (SPARCstation-4/5 + deriv.) + Format: noidle + Disable APC CPU standby support. SPARCstation-Fox does + not play well with APC CPU idle - disable it if you have + APC and your system crashes randomly. + + apic= [APIC,X86-32] Advanced Programmable Interrupt Controller + Change the output verbosity whilst booting + Format: { quiet (default) | verbose | debug } + Change the amount of debugging information output + when initialising the APIC and IO-APIC components. + + autoconf= [IPV6] + See Documentation/networking/ipv6.txt. + + show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller + Limit apic dumping. The parameter defines the maximal + number of local apics being dumped. Also it is possible + to set it to "all" by meaning -- no limit here. + Format: { 1 (default) | 2 | ... | all }. + The parameter valid if only apic=debug or + apic=verbose is specified. + Example: apic=debug show_lapic=all + + apm= [APM] Advanced Power Management + See header of arch/x86/kernel/apm_32.c. + + arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards + Format: <io>,<irq>,<nodeID> + + ataflop= [HW,M68k] + + atarimouse= [HW,MOUSE] Atari Mouse + + atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess, + EzKey and similar keyboards + + atkbd.reset= [HW] Reset keyboard during initialization + + atkbd.set= [HW] Select keyboard code set + Format: <int> (2 = AT (default), 3 = PS/2) + + atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar + keyboards + + atkbd.softraw= [HW] Choose between synthetic and real raw mode + Format: <bool> (0 = real, 1 = synthetic (default)) + + atkbd.softrepeat= [HW] + Use software keyboard repeat + + autotest [IA64] + + baycom_epp= [HW,AX25] + Format: <io>,<mode> + + baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem + Format: <io>,<mode> + See header of drivers/net/hamradio/baycom_par.c. + + baycom_ser_fdx= [HW,AX25] + BayCom Serial Port AX.25 Modem (Full Duplex Mode) + Format: <io>,<irq>,<mode>[,<baud>] + See header of drivers/net/hamradio/baycom_ser_fdx.c. + + baycom_ser_hdx= [HW,AX25] + BayCom Serial Port AX.25 Modem (Half Duplex Mode) + Format: <io>,<irq>,<mode> + See header of drivers/net/hamradio/baycom_ser_hdx.c. + + boot_delay= Milliseconds to delay each printk during boot. + Values larger than 10 seconds (10000) are changed to + no delay (0). + Format: integer + + bootmem_debug [KNL] Enable bootmem allocator debug messages. + + bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) + bttv.radio= Most important insmod options are available as + kernel args too. + bttv.pll= See Documentation/video4linux/bttv/Insmod-options + bttv.tuner= and Documentation/video4linux/bttv/CARDLIST + + c101= [NET] Moxa C101 synchronous serial card + + cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection. + Sometimes CPU hardware bugs make them report the cache + size incorrectly. The kernel will attempt work arounds + to fix known problems, but for some CPUs it is not + possible to determine what the correct size should be. + This option provides an override for these situations. + + capability.disable= + [SECURITY] Disable capabilities. This would normally + be used only if an alternative security model is to be + configured. Potentially dangerous and should only be + used if you are entirely sure of the consequences. + + ccw_timeout_log [S390] + See Documentation/s390/CommonIO for details. + + cgroup_disable= [KNL] Disable a particular controller + Format: {name of the controller(s) to disable} + {Currently supported controllers - "memory"} + + checkreqprot [SELINUX] Set initial checkreqprot flag value. + Format: { "0" | "1" } + See security/selinux/Kconfig help text. + 0 -- check protection applied by kernel (includes + any implied execute protection). + 1 -- check protection requested by application. + Default value is set via a kernel config option. + Value can be changed at runtime via + /selinux/checkreqprot. + + cio_ignore= [S390] + See Documentation/s390/CommonIO for details. + + clock= [BUGS=X86-32, HW] gettimeofday clocksource override. + [Deprecated] + Forces specified clocksource (if available) to be used + when calculating gettimeofday(). If specified + clocksource is not available, it defaults to PIT. + Format: { pit | tsc | cyclone | pmtmr } + + clocksource= Override the default clocksource + Format: <string> + Override the default clocksource and use the clocksource + with the name specified. + Some clocksource names to choose from, depending on + the platform: + [all] jiffies (this is the base, fallback clocksource) + [ACPI] acpi_pm + [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2, + pxa_timer,timer3,32k_counter,timer0_1 + [AVR32] avr32 + [X86-32] pit,hpet,tsc,vmi-timer; + scx200_hrt on Geode; cyclone on IBM x440 + [MIPS] MIPS + [PARISC] cr16 + [S390] tod + [SH] SuperH + [SPARC64] tick + [X86-64] hpet,tsc + + clearcpuid=BITNUM [X86] + Disable CPUID feature X for the kernel. See + arch/x86/include/asm/cpufeature.h for the valid bit + numbers. Note the Linux specific bits are not necessarily + stable over kernel options, but the vendor specific + ones should be. + Also note that user programs calling CPUID directly + or using the feature without checking anything + will still see it. This just prevents it from + being used by the kernel or shown in /proc/cpuinfo. + Also note the kernel might malfunction if you disable + some critical bits. + + cma= [CMA] List of CMA regions. + See Documentation/contiguous-memory.txt for details. + + cma.map= [CMA] CMA mapping + See Documentation/contiguous-memory.txt for details. + + cmo_free_hint= [PPC] Format: { yes | no } + Specify whether pages are marked as being inactive + when they are freed. This is used in CMO environments + to determine OS memory pressure for page stealing by + a hypervisor. + Default: yes + + code_bytes [X86] How many bytes of object code to print + in an oops report. + Range: 0 - 8192 + Default: 64 + + com20020= [HW,NET] ARCnet - COM20020 chipset + Format: + <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]] + + com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers) + Format: <io>[,<irq>] + + com90xx= [HW,NET] + ARCnet - COM90xx chipset (memory-mapped buffers) + Format: <io>[,<irq>[,<memstart>]] + + condev= [HW,S390] console device + conmode= + + console= [KNL] Output console device and options. + + tty<n> Use the virtual console device <n>. + + ttyS<n>[,options] + ttyUSB0[,options] + Use the specified serial port. The options are of + the form "bbbbpnf", where "bbbb" is the baud rate, + "p" is parity ("n", "o", or "e"), "n" is number of + bits, and "f" is flow control ("r" for RTS or + omit it). Default is "9600n8". + + See Documentation/serial-console.txt for more + information. See + Documentation/networking/netconsole.txt for an + alternative. + + uart[8250],io,<addr>[,options] + uart[8250],mmio,<addr>[,options] + Start an early, polled-mode console on the 8250/16550 + UART at the specified I/O port or MMIO address, + switching to the matching ttyS device later. The + options are the same as for ttyS, above. + + If the device connected to the port is not a TTY but a braille + device, prepend "brl," before the device type, for instance + console=brl,ttyS0 + For now, only VisioBraille is supported. + + consoleblank= [KNL] The console blank (screen saver) timeout in + seconds. Defaults to 10*60 = 10mins. A value of 0 + disables the blank timer. + + coredump_filter= + [KNL] Change the default value for + /proc/<pid>/coredump_filter. + See also Documentation/filesystems/proc.txt. + + cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver + Format: + <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] + + crashkernel=nn[KMG]@ss[KMG] + [KNL] Reserve a chunk of physical memory to + hold a kernel to switch to with kexec on panic. + + crashkernel=range1:size1[,range2:size2,...][@offset] + [KNL] Same as above, but depends on the memory + in the running system. The syntax of range is + start-[end] where start and end are both + a memory unit (amount[KMG]). See also + Documentation/kdump/kdump.txt for a example. + + cs89x0_dma= [HW,NET] + Format: <dma> + + cs89x0_media= [HW,NET] + Format: { rj45 | aui | bnc } + + dasd= [HW,NET] + See header of drivers/s390/block/dasd_devmap.c. + + db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port + (one device per port) + Format: <port#>,<type> + See also Documentation/input/joystick-parport.txt + + debug [KNL] Enable kernel debugging (events log level). + + debug_locks_verbose= + [KNL] verbose self-tests + Format=<0|1> + Print debugging info while doing the locking API + self-tests. + We default to 0 (no extra messages), setting it to + 1 will print _a lot_ more information - normally + only useful to kernel developers. + + debug_objects [KNL] Enable object debugging + + no_debug_objects + [KNL] Disable object debugging + + debugpat [X86] Enable PAT debugging + + decnet.addr= [HW,NET] + Format: <area>[,<node>] + See also Documentation/networking/decnet.txt. + + default_hugepagesz= + [same as hugepagesz=] The size of the default + HugeTLB page size. This is the size represented by + the legacy /proc/ hugepages APIs, used for SHM, and + default size when mounting hugetlbfs filesystems. + Defaults to the default architecture's huge page size + if not specified. + + dhash_entries= [KNL] + Set number of hash buckets for dentry cache. + + digi= [HW,SERIAL] + IO parameters + enable/disable command. + + digiepca= [HW,SERIAL] + See drivers/char/README.epca and + Documentation/serial/digiepca.txt. + + disable= [IPV6] + See Documentation/networking/ipv6.txt. + + disable_ipv6= [IPV6] + See Documentation/networking/ipv6.txt. + + disable_mtrr_cleanup [X86] + The kernel tries to adjust MTRR layout from continuous + to discrete, to make X server driver able to add WB + entry later. This parameter disables that. + + disable_mtrr_trim [X86, Intel and AMD only] + By default the kernel will trim any uncacheable + memory out of your available memory pool based on + MTRR settings. This parameter disables that behavior, + possibly causing your machine to run very slowly. + + disable_timer_pin_1 [X86] + Disable PIN 1 of APIC timer + Can be useful to work around chipset bugs. + + dma_debug=off If the kernel is compiled with DMA_API_DEBUG support, + this option disables the debugging code at boot. + + dma_debug_entries=<number> + This option allows to tune the number of preallocated + entries for DMA-API debugging code. One entry is + required per DMA-API allocation. Use this if the + DMA-API debugging code disables itself because the + architectural default is too low. + + dma_debug_driver=<driver_name> + With this option the DMA-API debugging driver + filter feature can be enabled at boot time. Just + pass the driver to filter for as the parameter. + The filter can be disabled or changed to another + driver later using sysfs. + + dscc4.setup= [NET] + + dynamic_printk Enables pr_debug()/dev_dbg() calls if + CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. + These can also be switched on/off via + <debugfs>/dynamic_printk/modules + + earlycon= [KNL] Output early console device and options. + uart[8250],io,<addr>[,options] + uart[8250],mmio,<addr>[,options] + uart[8250],mmio32,<addr>[,options] + Start an early, polled-mode console on the 8250/16550 + UART at the specified I/O port or MMIO address. + MMIO inter-register address stride is either 8bit (mmio) + or 32bit (mmio32). + The options are the same as for ttyS, above. + + earlyprintk= [X86,SH,BLACKFIN] + earlyprintk=vga + earlyprintk=serial[,ttySn[,baudrate]] + earlyprintk=ttySn[,baudrate] + earlyprintk=dbgp[debugController#] + + Append ",keep" to not disable it when the real console + takes over. + + Only vga or serial or usb debug port at a time. + + Currently only ttyS0 and ttyS1 are supported. + + Interaction with the standard serial driver is not + very good. + + The VGA output is eventually overwritten by the real + console. + + ekgdboc= [X86,KGDB] Allow early kernel console debugging + ekgdboc=kbd + + This is desgined to be used in conjunction with + the boot argument: earlyprintk=vga + + edd= [EDD] + Format: {"off" | "on" | "skip[mbr]"} + + eisa_irq_edge= [PARISC,HW] + See header of drivers/parisc/eisa.c. + + elanfreq= [X86-32] + See comment before function elanfreq_setup() in + arch/x86/kernel/cpu/cpufreq/elanfreq.c. + + elevator= [IOSCHED] + Format: {"anticipatory" | "cfq" | "deadline" | "noop"} + See Documentation/block/as-iosched.txt and + Documentation/block/deadline-iosched.txt for details. + + elfcorehdr= [IA64,PPC,SH,X86] + Specifies physical address of start of kernel core + image elf header. Generally kexec loader will + pass this option to capture kernel. + See Documentation/kdump/kdump.txt for details. + + enable_mtrr_cleanup [X86] + The kernel tries to adjust MTRR layout from continuous + to discrete, to make X server driver able to add WB + entry later. This parameter enables that. + + enable_timer_pin_1 [X86] + Enable PIN 1 of APIC timer + Can be useful to work around chipset bugs + (in particular on some ATI chipsets). + The kernel tries to set a reasonable default. + + enforcing [SELINUX] Set initial enforcing status. + Format: {"0" | "1"} + See security/selinux/Kconfig help text. + 0 -- permissive (log only, no denials). + 1 -- enforcing (deny and log). + Default value is 0. + Value can be changed at runtime via /selinux/enforce. + + erst_disable [ACPI] + Disable Error Record Serialization Table (ERST) + support. + + ether= [HW,NET] Ethernet cards parameters + This option is obsoleted by the "netdev=" option, which + has equivalent usage. See its documentation for details. + + failslab= + fail_page_alloc= + fail_make_request=[KNL] + General fault injection mechanism. + Format: <interval>,<probability>,<space>,<times> + See also /Documentation/fault-injection/. + + floppy= [HW] + See Documentation/blockdev/floppy.txt. + + force_pal_cache_flush + [IA-64] Avoid check_sal_cache_flush which may hang on + buggy SAL_CACHE_FLUSH implementations. Using this + parameter will force ia64_sal_cache_flush to call + ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. + + ftrace=[tracer] + [FTRACE] will set and start the specified tracer + as early as possible in order to facilitate early + boot debugging. + + ftrace_dump_on_oops[=orig_cpu] + [FTRACE] will dump the trace buffers on oops. + If no parameter is passed, ftrace will dump + buffers of all CPUs, but if you pass orig_cpu, it will + dump only the buffer of the CPU that triggered the + oops. + + ftrace_filter=[function-list] + [FTRACE] Limit the functions traced by the function + tracer at boot up. function-list is a comma separated + list of functions. This list can be changed at run + time by the set_ftrace_filter file in the debugfs + tracing directory. + + ftrace_notrace=[function-list] + [FTRACE] Do not trace the functions specified in + function-list. This list can be changed at run time + by the set_ftrace_notrace file in the debugfs + tracing directory. + + ftrace_graph_filter=[function-list] + [FTRACE] Limit the top level callers functions traced + by the function graph tracer at boot up. + function-list is a comma separated list of functions + that can be changed at run time by the + set_graph_function file in the debugfs tracing directory. + + gamecon.map[2|3]= + [HW,JOY] Multisystem joystick and NES/SNES/PSX pad + support via parallel port (up to 5 devices per port) + Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5> + See also Documentation/input/joystick-parport.txt + + gamma= [HW,DRM] + + gart_fix_e820= [X86_64] disable the fix e820 for K8 GART + Format: off | on + default: on + + gcov_persist= [GCOV] When non-zero (default), profiling data for + kernel modules is saved and remains accessible via + debugfs, even when the module is unloaded/reloaded. + When zero, profiling data is discarded and associated + debugfs files are removed at module unload time. + + gpt [EFI] Forces disk with valid GPT signature but + invalid Protective MBR to be treated as GPT. + + hashdist= [KNL,NUMA] Large hashes allocated during boot + are distributed across NUMA nodes. Defaults on + for 64bit NUMA, off otherwise. + Format: 0 | 1 (for off | on) + + hcl= [IA-64] SGI's Hardware Graph compatibility layer + + hd= [EIDE] (E)IDE hard drive subsystem geometry + Format: <cyl>,<head>,<sect> + + hest_disable [ACPI] + Disable Hardware Error Source Table (HEST) support; + corresponding firmware-first mode error processing + logic will be disabled. + + highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact + size of <nn>. This works even on boxes that have no + highmem otherwise. This also works to reduce highmem + size on bigger boxes. + + highres= [KNL] Enable/disable high resolution timer mode. + Valid parameters: "on", "off" + Default: "on" + + hisax= [HW,ISDN] + See Documentation/isdn/README.HiSax. + + hlt [BUGS=ARM,SH] + + hpet= [X86-32,HPET] option to control HPET usage + Format: { enable (default) | disable | force | + verbose } + disable: disable HPET and use PIT instead + force: allow force enabled of undocumented chips (ICH4, + VIA, nVidia) + verbose: show contents of HPET registers during setup + + hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. + hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. + On x86-64 and powerpc, this option can be specified + multiple times interleaved with hugepages= to reserve + huge pages of different sizes. Valid pages sizes on + x86-64 are 2M (when the CPU supports "pse") and 1G + (when the CPU supports the "pdpe1gb" cpuinfo flag) + Note that 1GB pages can only be allocated at boot time + using hugepages= and not freed afterwards. + + hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC) + terminal devices. Valid values: 0..8 + hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs. + If specified, z/VM IUCV HVC accepts connections + from listed z/VM user IDs only. + + i2c_bus= [HW] Override the default board specific I2C bus speed + or register an additional I2C bus that is not + registered from board initialization code. + Format: + <bus_id>,<clkrate> + + i8042.debug [HW] Toggle i8042 debug mode + i8042.direct [HW] Put keyboard port into non-translated mode + i8042.dumbkbd [HW] Pretend that controller can only read data from + keyboard and cannot control its state + (Don't attempt to blink the leds) + i8042.noaux [HW] Don't check for auxiliary (== mouse) port + i8042.nokbd [HW] Don't check/create keyboard port + i8042.noloop [HW] Disable the AUX Loopback command while probing + for the AUX port + i8042.nomux [HW] Don't check presence of an active multiplexing + controller + i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX + controllers + i8042.notimeout [HW] Ignore timeout condition signalled by conroller + i8042.reset [HW] Reset the controller during init and cleanup + i8042.unlock [HW] Unlock (ignore) the keylock + + i810= [HW,DRM] + + i8k.ignore_dmi [HW] Continue probing hardware even if DMI data + indicates that the driver is running on unsupported + hardware. + i8k.force [HW] Activate i8k driver even if SMM BIOS signature + does not match list of supported models. + i8k.power_status + [HW] Report power status in /proc/i8k + (disabled by default) + i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN + capability is set. + + icn= [HW,ISDN] + Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] + + ide-core.nodma= [HW] (E)IDE subsystem + Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc + .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr + .cdrom .chs .ignore_cable are additional options + See Documentation/ide/ide.txt. + + ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem + Claim all unknown PCI IDE storage controllers. + + idle= [X86] + Format: idle=poll, idle=mwait, idle=halt, idle=nomwait + Poll forces a polling idle loop that can slightly + improve the performance of waking up a idle CPU, but + will use a lot of power and make the system run hot. + Not recommended. + idle=mwait: On systems which support MONITOR/MWAIT but + the kernel chose to not use it because it doesn't save + as much power as a normal idle loop, use the + MONITOR/MWAIT idle loop anyways. Performance should be + the same as idle=poll. + idle=halt: Halt is forced to be used for CPU idle. + In such case C2/C3 won't be used again. + idle=nomwait: Disable mwait for CPU C-states + + ignore_loglevel [KNL] + Ignore loglevel setting - this will print /all/ + kernel messages to the console. Useful for debugging. + + ihash_entries= [KNL] + Set number of hash buckets for inode cache. + + ima_audit= [IMA] + Format: { "0" | "1" } + 0 -- integrity auditing messages. (Default) + 1 -- enable informational integrity auditing messages. + + ima_hash= [IMA] + Format: { "sha1" | "md5" } + default: "sha1" + + ima_tcb [IMA] + Load a policy which meets the needs of the Trusted + Computing Base. This means IMA will measure all + programs exec'd, files mmap'd for exec, and all files + opened for read by uid=0. + + init= [KNL] + Format: <full_path> + Run specified binary instead of /sbin/init as init + process. + + initcall_debug [KNL] Trace initcalls as they are executed. Useful + for working out where the kernel is dying during + startup. + + initrd= [BOOT] Specify the location of the initial ramdisk + + inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver + Format: <irq> + + intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option + on + Enable intel iommu driver. + off + Disable intel iommu driver. + igfx_off [Default Off] + By default, gfx is mapped as normal device. If a gfx + device has a dedicated DMAR unit, the DMAR unit is + bypassed by not enabling DMAR with this option. In + this case, gfx device will use physical address for + DMA. + forcedac [x86_64] + With this option iommu will not optimize to look + for io virtual address below 32 bit forcing dual + address cycle on pci bus for cards supporting greater + than 32 bit addressing. The default is to look + for translation below 32 bit and if not available + then look in the higher range. + strict [Default Off] + With this option on every unmap_single operation will + result in a hardware IOTLB flush operation as opposed + to batching them for performance. + + intremap= [X86-64, Intel-IOMMU] + Format: { on (default) | off | nosid } + on enable Interrupt Remapping (default) + off disable Interrupt Remapping + nosid disable Source ID checking + + inttest= [IA64] + + iomem= Disable strict checking of access to MMIO memory + strict regions from userspace. + relaxed + + iommu= [x86] + off + force + noforce + biomerge + panic + nopanic + merge + nomerge + forcesac + soft + pt [x86, IA64] + + io7= [HW] IO7 for Marvel based alpha systems + See comment before marvel_specify_io7 in + arch/alpha/kernel/core_marvel.c. + + io_delay= [X86] I/O delay method + 0x80 + Standard port 0x80 based delay + 0xed + Alternate port 0xed based delay (needed on some systems) + udelay + Simple two microseconds delay + none + No delay + + ip= [IP_PNP] + See Documentation/filesystems/nfs/nfsroot.txt. + + ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards + See comment before ip2_setup() in + drivers/char/ip2/ip2base.c. + + irqfixup [HW] + When an interrupt is not handled search all handlers + for it. Intended to get systems with badly broken + firmware running. + + irqpoll [HW] + When an interrupt is not handled search all handlers + for it. Also check all handlers each timer + interrupt. Intended to get systems with badly broken + firmware running. + + isapnp= [ISAPNP] + Format: <RDP>,<reset>,<pci_scan>,<verbosity> + + isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. + Format: + <cpu number>,...,<cpu number> + or + <cpu number>-<cpu number> + (must be a positive range in ascending order) + or a mixture + <cpu number>,...,<cpu number>-<cpu number> + + This option can be used to specify one or more CPUs + to isolate from the general SMP balancing and scheduling + algorithms. You can move a process onto or off an + "isolated" CPU via the CPU affinity syscalls or cpuset. + <cpu number> begins at 0 and the maximum value is + "number of CPUs in system - 1". + + This option is the preferred way to isolate CPUs. The + alternative -- manually setting the CPU mask of all + tasks in the system -- can cause problems and + suboptimal load balancer performance. + + iucv= [HW,NET] + + js= [HW,JOY] Analog joystick + See Documentation/input/joystick.txt. + + keepinitrd [HW,ARM] + + kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter + specifies the amount of memory usable by the kernel + for non-movable allocations. The requested amount is + spread evenly throughout all nodes in the system. The + remaining memory in each node is used for Movable + pages. In the event, a node is too small to have both + kernelcore and Movable pages, kernelcore pages will + take priority and other nodes will have a larger number + of kernelcore pages. The Movable zone is used for the + allocation of pages that may be reclaimed or moved + by the page migration subsystem. This means that + HugeTLB pages may not be allocated from this zone. + Note that allocations like PTEs-from-HighMem still + use the HighMem zone if it exists, and the Normal + zone if it does not. + + kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. + Format: <Controller#>[,poll interval] + The controller # is the number of the ehci usb debug + port as it is probed via PCI. The poll interval is + optional and is the number seconds in between + each poll cycle to the debug port in case you need + the functionality for interrupting the kernel with + gdb or control-c on the dbgp connection. When + not using this parameter you use sysrq-g to break into + the kernel debugger. + + kgdboc= [KGDB,HW] kgdb over consoles. + Requires a tty driver that supports console polling, + or a supported polling keyboard driver (non-usb). + Serial only format: <serial_device>[,baud] + keyboard only format: kbd + keyboard and serial format: kbd,<serial_device>[,baud] + Optional Kernel mode setting: + kms, kbd format: kms,kbd + kms, kbd and serial format: kms,kbd,<ser_dev>[,baud] + + kgdbwait [KGDB] Stop kernel execution and enter the + kernel debugger at the earliest opportunity. + + kmac= [MIPS] korina ethernet MAC address. + Configure the RouterBoard 532 series on-chip + Ethernet adapter MAC address. + + kmemleak= [KNL] Boot-time kmemleak enable/disable + Valid arguments: on, off + Default: on + + kstack=N [X86] Print N words from the kernel stack + in oops dumps. + + kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. + Default is 0 (don't ignore, but inject #GP) + + kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging. + Default is 1 (enabled) + + kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM. + Default is 0 (off) + + kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU) + for all guests. + Default is 1 (enabled) if in 64bit or 32bit-PAE mode + + kvm-intel.bypass_guest_pf= + [KVM,Intel] Disables bypassing of guest page faults + on Intel chips. Default is 1 (enabled) + + kvm-intel.ept= [KVM,Intel] Disable extended page tables + (virtualized MMU) support on capable Intel chips. + Default is 1 (enabled) + + kvm-intel.emulate_invalid_guest_state= + [KVM,Intel] Enable emulation of invalid guest states + Default is 0 (disabled) + + kvm-intel.flexpriority= + [KVM,Intel] Disable FlexPriority feature (TPR shadow). + Default is 1 (enabled) + + kvm-intel.unrestricted_guest= + [KVM,Intel] Disable unrestricted guest feature + (virtualized real and unpaged mode) on capable + Intel chips. Default is 1 (enabled) + + kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification + feature (tagged TLBs) on capable Intel chips. + Default is 1 (enabled) + + l2cr= [PPC] + + l3cr= [PPC] + + lapic [X86-32,APIC] Enable the local APIC even if BIOS + disabled it. + + lapic_timer_c2_ok [X86,APIC] trust the local apic timer + in C2 power state. + + libata.dma= [LIBATA] DMA control + libata.dma=0 Disable all PATA and SATA DMA + libata.dma=1 PATA and SATA Disk DMA only + libata.dma=2 ATAPI (CDROM) DMA only + libata.dma=4 Compact Flash DMA only + Combinations also work, so libata.dma=3 enables DMA + for disks and CDROMs, but not CFs. + + libata.ignore_hpa= [LIBATA] Ignore HPA limit + libata.ignore_hpa=0 keep BIOS limits (default) + libata.ignore_hpa=1 ignore limits, using full disk + + libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume + when set. + Format: <int> + + libata.force= [LIBATA] Force configurations. The format is comma + separated list of "[ID:]VAL" where ID is + PORT[.DEVICE]. PORT and DEVICE are decimal numbers + matching port, link or device. Basically, it matches + the ATA ID string printed on console by libata. If + the whole ID part is omitted, the last PORT and DEVICE + values are used. If ID hasn't been specified yet, the + configuration applies to all ports, links and devices. + + If only DEVICE is omitted, the parameter applies to + the port and all links and devices behind it. DEVICE + number of 0 either selects the first device or the + first fan-out link behind PMP device. It does not + select the host link. DEVICE number of 15 selects the + host link and device attached to it. + + The VAL specifies the configuration to force. As long + as there's no ambiguity shortcut notation is allowed. + For example, both 1.5 and 1.5G would work for 1.5Gbps. + The following configurations can be forced. + + * Cable type: 40c, 80c, short40c, unk, ign or sata. + Any ID with matching PORT is used. + + * SATA link speed limit: 1.5Gbps or 3.0Gbps. + + * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7]. + udma[/][16,25,33,44,66,100,133] notation is also + allowed. + + * [no]ncq: Turn on or off NCQ. + + * nohrst, nosrst, norst: suppress hard, soft + and both resets. + + * dump_id: dump IDENTIFY data. + + If there are multiple matching configurations changing + the same attribute, the last one is used. + + memblock=debug [KNL] Enable memblock debug messages. + + load_ramdisk= [RAM] List of ramdisks to load from floppy + See Documentation/blockdev/ramdisk.txt. + + lockd.nlm_grace_period=P [NFS] Assign grace period. + Format: <integer> + + lockd.nlm_tcpport=N [NFS] Assign TCP port. + Format: <integer> + + lockd.nlm_timeout=T [NFS] Assign timeout value. + Format: <integer> + + lockd.nlm_udpport=M [NFS] Assign UDP port. + Format: <integer> + + logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver + Format: <irq> + + loglevel= All Kernel Messages with a loglevel smaller than the + console loglevel will be printed to the console. It can + also be changed with klogd or other programs. The + loglevels are defined as follows: + + 0 (KERN_EMERG) system is unusable + 1 (KERN_ALERT) action must be taken immediately + 2 (KERN_CRIT) critical conditions + 3 (KERN_ERR) error conditions + 4 (KERN_WARNING) warning conditions + 5 (KERN_NOTICE) normal but significant condition + 6 (KERN_INFO) informational + 7 (KERN_DEBUG) debug-level messages + + log_buf_len=n Sets the size of the printk ring buffer, in bytes. + Format: { n | nk | nM } + n must be a power of two. The default size + is set in the kernel config file. + + logo.nologo [FB] Disables display of the built-in Linux logo. + This may be used to provide more screen space for + kernel log messages and is useful when debugging + kernel boot problems. + + lp=0 [LP] Specify parallel ports to use, e.g, + lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses + lp=reset first parallel port). 'lp=0' disables the + lp=auto printer driver. 'lp=reset' (which can be + specified in addition to the ports) causes + attached printers to be reset. Using + lp=port1,port2,... specifies the parallel ports + to associate lp devices with, starting with + lp0. A port specification may be 'none' to skip + that lp device, or a parport name such as + 'parport0'. Specifying 'lp=auto' instead of a + port specification list means that device IDs + from each port should be examined, to see if + an IEEE 1284-compliant printer is attached; if + so, the driver will manage that printer. + See also header of drivers/char/lp.c. + + lpj=n [KNL] + Sets loops_per_jiffy to given constant, thus avoiding + time-consuming boot-time autodetection (up to 250 ms per + CPU). 0 enables autodetection (default). To determine + the correct value for your kernel, boot with normal + autodetection and see what value is printed. Note that + on SMP systems the preset will be applied to all CPUs, + which is likely to cause problems if your CPUs need + significantly divergent settings. An incorrect value + will cause delays in the kernel to be wrong, leading to + unpredictable I/O errors and other breakage. Although + unlikely, in the extreme case this might damage your + hardware. + + ltpc= [NET] + Format: <io>,<irq>,<dma> + + machvec= [IA64] Force the use of a particular machine-vector + (machvec) in a generic kernel. + Example: machvec=hpzx1_swiotlb + + machtype= [Loongson] Share the same kernel image file between different + yeeloong laptop. + Example: machtype=lemote-yeeloong-2f-7inch + + max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater + than or equal to this physical address is ignored. + + maxcpus= [SMP] Maximum number of processors that an SMP kernel + should make use of. maxcpus=n : n >= 0 limits the + kernel to using 'n' processors. n=0 is a special case, + it is equivalent to "nosmp", which also disables + the IO APIC. + + max_loop= [LOOP] Maximum number of loopback devices that can + be mounted + Format: <1-256> + + mcatest= [IA-64] + + mce [X86-32] Machine Check Exception + + mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt + + md= [HW] RAID subsystems devices and level + See Documentation/md.txt. + + mdacon= [MDA] + Format: <first>,<last> + Specifies range of consoles to be captured by the MDA. + + mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory + Amount of memory to be used when the kernel is not able + to see the whole system memory or for test. + [X86-32] Use together with memmap= to avoid physical + address space collisions. Without memmap= PCI devices + could be placed at addresses belonging to unused RAM. + + mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel + memory. + + memchunk=nn[KMG] + [KNL,SH] Allow user to override the default size for + per-device physically contiguous DMA buffers. + + memmap=exactmap [KNL,X86] Enable setting of an exact + E820 memory map, as specified by the user. + Such memmap=exactmap lines can be constructed based on + BIOS output or other requirements. See the memmap=nn@ss + option description. + + memmap=nn[KMG]@ss[KMG] + [KNL] Force usage of a specific region of memory + Region of memory to be used, from ss to ss+nn. + + memmap=nn[KMG]#ss[KMG] + [KNL,ACPI] Mark specific memory as ACPI data. + Region of memory to be used, from ss to ss+nn. + + memmap=nn[KMG]$ss[KMG] + [KNL,ACPI] Mark specific memory as reserved. + Region of memory to be used, from ss to ss+nn. + Example: Exclude memory from 0x18690000-0x1869ffff + memmap=64K$0x18690000 + or + memmap=0x10000$0x18690000 + + memory_corruption_check=0/1 [X86] + Some BIOSes seem to corrupt the first 64k of + memory when doing things like suspend/resume. + Setting this option will scan the memory + looking for corruption. Enabling this will + both detect corruption and prevent the kernel + from using the memory being corrupted. + However, its intended as a diagnostic tool; if + repeatable BIOS-originated corruption always + affects the same memory, you can use memmap= + to prevent the kernel from using that memory. + + memory_corruption_check_size=size [X86] + By default it checks for corruption in the low + 64k, making this memory unavailable for normal + use. Use this parameter to scan for + corruption in more or less memory. + + memory_corruption_check_period=seconds [X86] + By default it checks for corruption every 60 + seconds. Use this parameter to check at some + other rate. 0 disables periodic checking. + + memtest= [KNL,X86] Enable memtest + Format: <integer> + default : 0 <disable> + Specifies the number of memtest passes to be + performed. Each pass selects another test + pattern from a given set of patterns. Memtest + fills the memory with this pattern, validates + memory contents and reserves bad memory + regions that are detected. + + meye.*= [HW] Set MotionEye Camera parameters + See Documentation/video4linux/meye.txt. + + mfgpt_irq= [IA-32] Specify the IRQ to use for the + Multi-Function General Purpose Timers on AMD Geode + platforms. + + mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when + the BIOS has incorrectly applied a workaround. TinyBIOS + version 0.98 is known to be affected, 0.99 fixes the + problem by letting the user disable the workaround. + + mga= [HW,DRM] + + min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this + physical address is ignored. + + mini2440= [ARM,HW,KNL] + Format:[0..2][b][c][t] + Default: "0tb" + MINI2440 configuration specification: + 0 - The attached screen is the 3.5" TFT + 1 - The attached screen is the 7" TFT + 2 - The VGA Shield is attached (1024x768) + Leaving out the screen size parameter will not load + the TFT driver, and the framebuffer will be left + unconfigured. + b - Enable backlight. The TFT backlight pin will be + linked to the kernel VESA blanking code and a GPIO + LED. This parameter is not necessary when using the + VGA shield. + c - Enable the s3c camera interface. + t - Reserved for enabling touchscreen support. The + touchscreen support is not enabled in the mainstream + kernel as of 2.6.30, a preliminary port can be found + in the "bleeding edge" mini2440 support kernel at + http://repo.or.cz/w/linux-2.6/mini2440.git + + mminit_loglevel= + [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this + parameter allows control of the logging verbosity for + the additional memory initialisation checks. A value + of 0 disables mminit logging and a level of 4 will + log everything. Information is printed at KERN_DEBUG + so loglevel=8 may also need to be specified. + + mousedev.tap_time= + [MOUSE] Maximum time between finger touching and + leaving touchpad surface for touch to be considered + a tap and be reported as a left button click (for + touchpads working in absolute mode only). + Format: <msecs> + mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices + reporting absolute coordinates, such as tablets + mousedev.yres= [MOUSE] Vertical screen resolution, used for devices + reporting absolute coordinates, such as tablets + + movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter + is similar to kernelcore except it specifies the + amount of memory used for migratable allocations. + If both kernelcore and movablecore is specified, + then kernelcore will be at *least* the specified + value but may be more. If movablecore on its own + is specified, the administrator must be careful + that the amount of memory usable for all allocations + is not too small. + + MTD_Partition= [MTD] + Format: <name>,<region-number>,<size>,<offset> + + MTD_Region= [MTD] Format: + <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] + + mtdparts= [MTD] + See drivers/mtd/cmdlinepart.c. + + onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration + + Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] + + boundary - index of last SLC block on Flex-OneNAND. + The remaining blocks are configured as MLC blocks. + lock - Configure if Flex-OneNAND boundary should be locked. + Once locked, the boundary cannot be changed. + 1 indicates lock status, 0 indicates unlock status. + + mtdset= [ARM] + ARM/S3C2412 JIVE boot control + + See arch/arm/mach-s3c2412/mach-jive.c + + mtouchusb.raw_coordinates= + [HW] Make the MicroTouch USB driver use raw coordinates + ('y', default) or cooked coordinates ('n') + + mtrr_chunk_size=nn[KMG] [X86] + used for mtrr cleanup. It is largest continuous chunk + that could hold holes aka. UC entries. + + mtrr_gran_size=nn[KMG] [X86] + Used for mtrr cleanup. It is granularity of mtrr block. + Default is 1. + Large value could prevent small alignment from + using up MTRRs. + + mtrr_spare_reg_nr=n [X86] + Format: <integer> + Range: 0,7 : spare reg number + Default : 1 + Used for mtrr cleanup. It is spare mtrr entries number. + Set to 2 or more if your graphical card needs more. + + n2= [NET] SDL Inc. RISCom/N2 synchronous serial card + + netdev= [NET] Network devices parameters + Format: <irq>,<io>,<mem_start>,<mem_end>,<name> + Note that mem_start is often overloaded to mean + something different and driver-specific. + This usage is only documented in each driver source + file if at all. + + nf_conntrack.acct= + [NETFILTER] Enable connection tracking flow accounting + 0 to disable accounting + 1 to enable accounting + Default value is 0. + + nfsaddrs= [NFS] + See Documentation/filesystems/nfs/nfsroot.txt. + + nfsroot= [NFS] nfs root filesystem for disk-less boxes. + See Documentation/filesystems/nfs/nfsroot.txt. + + nfs.callback_tcpport= + [NFS] set the TCP port on which the NFSv4 callback + channel should listen. + + nfs.cache_getent= + [NFS] sets the pathname to the program which is used + to update the NFS client cache entries. + + nfs.cache_getent_timeout= + [NFS] sets the timeout after which an attempt to + update a cache entry is deemed to have failed. + + nfs.idmap_cache_timeout= + [NFS] set the maximum lifetime for idmapper cache + entries. + + nfs.enable_ino64= + [NFS] enable 64-bit inode numbers. + If zero, the NFS client will fake up a 32-bit inode + number for the readdir() and stat() syscalls instead + of returning the full 64-bit number. + The default is to return 64-bit inode numbers. + + nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take + when a NMI is triggered. + Format: [state][,regs][,debounce][,die] + + nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels + Format: [panic,][num] + Valid num: 0,1,2 + 0 - turn nmi_watchdog off + 1 - use the IO-APIC timer for the NMI watchdog + 2 - use the local APIC for the NMI watchdog using + a performance counter. Note: This will use one + performance counter and the local APIC's performance + vector. + When panic is specified, panic when an NMI watchdog + timeout occurs. + This is useful when you use a panic=... timeout and + need the box quickly up again. + Instead of 1 and 2 it is possible to use the following + symbolic names: lapic and ioapic + Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic + + netpoll.carrier_timeout= + [NET] Specifies amount of time (in seconds) that + netpoll should wait for a carrier. By default netpoll + waits 4 seconds. + + no387 [BUGS=X86-32] Tells the kernel to use the 387 maths + emulation library even if a 387 maths coprocessor + is present. + + no_console_suspend + [HW] Never suspend the console + Disable suspending of consoles during suspend and + hibernate operations. Once disabled, debugging + messages can reach various consoles while the rest + of the system is being put to sleep (ie, while + debugging driver suspend/resume hooks). This may + not work reliably with all consoles, but is known + to work with serial and VGA consoles. + + noaliencache [MM, NUMA, SLAB] Disables the allocation of alien + caches in the slab allocator. Saves per-node memory, + but will impact performance. + + noalign [KNL,ARM] + + noapic [SMP,APIC] Tells the kernel to not make use of any + IOAPICs that may be present in the system. + + nobats [PPC] Do not use BATs for mapping kernel lowmem + on "Classic" PPC cores. + + nocache [ARM] + + noclflush [BUGS=X86] Don't use the CLFLUSH instruction + + nodelayacct [KNL] Disable per-task delay accounting + + nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. + + nodsp [SH] Disable hardware DSP at boot time. + + noefi [X86] Disable EFI runtime services support. + + noexec [IA-64] + + noexec [X86] + On X86-32 available only on PAE configured kernels. + noexec=on: enable non-executable mappings (default) + noexec=off: disable non-executable mappings + + noexec32 [X86-64] + This affects only 32-bit executables. + noexec32=on: enable non-executable mappings (default) + read doesn't imply executable mappings + noexec32=off: disable non-executable mappings + read implies executable mappings + + nofpu [SH] Disable hardware FPU at boot time. + + nofxsr [BUGS=X86-32] Disables x86 floating point extended + register save and restore. The kernel will only save + legacy floating-point registers on task switch. + + noxsave [BUGS=X86] Disables x86 extended register state save + and restore using xsave. The kernel will fallback to + enabling legacy floating-point and sse state. + + nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or + wfi(ARM) instruction doesn't work correctly and not to + use it. This is also useful when using JTAG debugger. + + no-hlt [BUGS=X86-32] Tells the kernel that the hlt + instruction doesn't work correctly and not to + use it. + + no_file_caps Tells the kernel not to honor file capabilities. The + only way then for a file to be executed with privilege + is to be setuid root or executed by root. + + nohalt [IA-64] Tells the kernel not to use the power saving + function PAL_HALT_LIGHT when idle. This increases + power-consumption. On the positive side, it reduces + interrupt wake-up latency, which may improve performance + in certain environments such as networked servers or + real-time systems. + + nohz= [KNL] Boottime enable/disable dynamic ticks + Valid arguments: on, off + Default: on + + noiotrap [SH] Disables trapped I/O port accesses. + + noirqdebug [X86-32] Disables the code which attempts to detect and + disable unhandled interrupt sources. + + no_timer_check [X86,APIC] Disables the code which tests for + broken timer IRQ sources. + + noisapnp [ISAPNP] Disables ISA PnP code. + + noinitrd [RAM] Tells the kernel not to load any configured + initial RAM disk. + + nointremap [X86-64, Intel-IOMMU] Do not enable interrupt + remapping. + [Deprecated - use intremap=off] + + nointroute [IA-64] + + nojitter [IA64] Disables jitter checking for ITC timers. + + nolapic [X86-32,APIC] Do not enable or use the local APIC. + + nolapic_timer [X86-32,APIC] Do not use the local APIC timer. + + noltlbs [PPC] Do not use large page/tlb entries for kernel + lowmem mapping on PPC40x. + + nomca [IA-64] Disable machine check abort handling + + nomce [X86-32] Machine Check Exception + + nomfgpt [X86-32] Disable Multi-Function General Purpose + Timer usage (for AMD Geode machines). + + nopat [X86] Disable PAT (page attribute table extension of + pagetables) support. + + norandmaps Don't use address space randomization. Equivalent to + echo 0 > /proc/sys/kernel/randomize_va_space + + noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops + + noreplace-smp [X86-32,SMP] Don't replace SMP instructions + with UP alternatives + + noresidual [PPC] Don't use residual data on PReP machines. + + noresume [SWSUSP] Disables resume and restores original swap + space. + + no-scroll [VGA] Disables scrollback. + This is required for the Braillex ib80-piezo Braille + reader made by F.H. Papenmeier (Germany). + + nosbagart [IA-64] + + nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. + + nosmp [SMP] Tells an SMP kernel to act as a UP kernel, + and disable the IO APIC. legacy for "maxcpus=0". + + nosoftlockup [KNL] Disable the soft-lockup detector. + + noswapaccount [KNL] Disable accounting of swap in memory resource + controller. (See Documentation/cgroups/memory.txt) + + nosync [HW,M68K] Disables sync negotiation for all devices. + + notsc [BUGS=X86-32] Disable Time Stamp Counter + + nousb [USB] Disable the USB subsystem + + nowatchdog [KNL] Disable the lockup detector (NMI watchdog). + + nowb [ARM] + + nox2apic [X86-64,APIC] Do not enable x2APIC mode. + + nptcg= [IA64] Override max number of concurrent global TLB + purges which is reported from either PAL_VM_SUMMARY or + SAL PALO. + + nr_cpus= [SMP] Maximum number of processors that an SMP kernel + could support. nr_cpus=n : n >= 1 limits the kernel to + supporting 'n' processors. Later in runtime you can not + use hotplug cpu feature to put more cpu back to online. + just like you compile the kernel NR_CPUS=n + + nr_uarts= [SERIAL] maximum number of UARTs to be registered. + + numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. + one of ['zone', 'node', 'default'] can be specified + This can be set from sysctl after boot. + See Documentation/sysctl/vm.txt for details. + + ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. + See Documentation/debugging-via-ohci1394.txt for more + info. + + olpc_ec_timeout= [OLPC] ms delay when issuing EC commands + Rather than timing out after 20 ms if an EC + command is not properly ACKed, override the length + of the timeout. We have interrupts disabled while + waiting for the ACK, so if this is set too high + interrupts *may* be lost! + + omap_mux= [OMAP] Override bootloader pin multiplexing. + Format: <mux_mode0.mode_name=value>... + For example, to override I2C bus2: + omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 + + oprofile.timer= [HW] + Use timer interrupt instead of performance counters + + oprofile.cpu_type= Force an oprofile cpu type + This might be useful if you have an older oprofile + userland or if you want common events. + Format: { arch_perfmon } + arch_perfmon: [X86] Force use of architectural + perfmon on Intel CPUs instead of the + CPU specific event set. + + OSS [HW,OSS] + See Documentation/sound/oss/oss-parameters.txt + + panic= [KNL] Kernel behaviour on panic + Format: <timeout> + + parkbd.port= [HW] Parallel port number the keyboard adapter is + connected to, default is 0. + Format: <parport#> + parkbd.mode= [HW] Parallel port keyboard adapter mode of operation, + 0 for XT, 1 for AT (default is AT). + Format: <mode> + + parport= [HW,PPT] Specify parallel ports. 0 disables. + Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] } + Use 'auto' to force the driver to use any + IRQ/DMA settings detected (the default is to + ignore detected IRQ/DMA settings because of + possible conflicts). You can specify the base + address, IRQ, and DMA settings; IRQ and DMA + should be numbers, or 'auto' (for using detected + settings on that particular port), or 'nofifo' + (to avoid using a FIFO even if it is detected). + Parallel ports are assigned in the order they + are specified on the command line, starting + with parport0. + + parport_init_mode= [HW,PPT] + Configure VIA parallel port to operate in + a specific mode. This is necessary on Pegasos + computer where firmware has no options for setting + up parallel port mode and sets it to spp. + Currently this function knows 686a and 8231 chips. + Format: [spp|ps2|epp|ecp|ecpepp] + + pause_on_oops= + Halt all CPUs after the first oops has been printed for + the specified number of seconds. This is to be used if + your oopses keep scrolling off the screen. + + pcbit= [HW,ISDN] + + pcd. [PARIDE] + See header of drivers/block/paride/pcd.c. + See also Documentation/blockdev/paride.txt. + + pci=option[,option...] [PCI] various PCI subsystem options: + earlydump [X86] dump PCI config space before the kernel + changes anything + off [X86] don't probe for the PCI bus + bios [X86-32] force use of PCI BIOS, don't access + the hardware directly. Use this if your machine + has a non-standard PCI host bridge. + nobios [X86-32] disallow use of PCI BIOS, only direct + hardware access methods are allowed. Use this + if you experience crashes upon bootup and you + suspect they are caused by the BIOS. + conf1 [X86] Force use of PCI Configuration + Mechanism 1. + conf2 [X86] Force use of PCI Configuration + Mechanism 2. + noaer [PCIE] If the PCIEAER kernel config parameter is + enabled, this kernel boot option can be used to + disable the use of PCIE advanced error reporting. + nodomains [PCI] Disable support for multiple PCI + root domains (aka PCI segments, in ACPI-speak). + nommconf [X86] Disable use of MMCONFIG for PCI + Configuration + check_enable_amd_mmconf [X86] check for and enable + properly configured MMIO access to PCI + config space on AMD family 10h CPU + nomsi [MSI] If the PCI_MSI kernel config parameter is + enabled, this kernel boot option can be used to + disable the use of MSI interrupts system-wide. + noioapicquirk [APIC] Disable all boot interrupt quirks. + Safety option to keep boot IRQs enabled. This + should never be necessary. + ioapicreroute [APIC] Enable rerouting of boot IRQs to the + primary IO-APIC for bridges that cannot disable + boot IRQs. This fixes a source of spurious IRQs + when the system masks IRQs. + noioapicreroute [APIC] Disable workaround that uses the + boot IRQ equivalent of an IRQ that connects to + a chipset where boot IRQs cannot be disabled. + The opposite of ioapicreroute. + biosirq [X86-32] Use PCI BIOS calls to get the interrupt + routing table. These calls are known to be buggy + on several machines and they hang the machine + when used, but on other computers it's the only + way to get the interrupt routing table. Try + this option if the kernel is unable to allocate + IRQs or discover secondary PCI buses on your + motherboard. + rom [X86] Assign address space to expansion ROMs. + Use with caution as certain devices share + address decoders between ROMs and other + resources. + norom [X86] Do not assign address space to + expansion ROMs that do not already have + BIOS assigned address ranges. + nobar [X86] Do not assign address space to the + BARs that weren't assigned by the BIOS. + irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be + assigned automatically to PCI devices. You can + make the kernel exclude IRQs of your ISA cards + this way. + pirqaddr=0xAAAAA [X86] Specify the physical address + of the PIRQ table (normally generated + by the BIOS) if it is outside the + F0000h-100000h range. + lastbus=N [X86] Scan all buses thru bus #N. Can be + useful if the kernel is unable to find your + secondary buses and you want to tell it + explicitly which ones they are. + assign-busses [X86] Always assign all PCI bus + numbers ourselves, overriding + whatever the firmware may have done. + usepirqmask [X86] Honor the possible IRQ mask stored + in the BIOS $PIR table. This is needed on + some systems with broken BIOSes, notably + some HP Pavilion N5400 and Omnibook XE3 + notebooks. This will have no effect if ACPI + IRQ routing is enabled. + noacpi [X86] Do not use ACPI for IRQ routing + or for PCI scanning. + use_crs [X86] Use PCI host bridge window information + from ACPI. On BIOSes from 2008 or later, this + is enabled by default. If you need to use this, + please report a bug. + nocrs [X86] Ignore PCI host bridge windows from ACPI. + If you need to use this, please report a bug. + routeirq Do IRQ routing for all PCI devices. + This is normally done in pci_enable_device(), + so this option is a temporary workaround + for broken drivers that don't call it. + skip_isa_align [X86] do not align io start addr, so can + handle more pci cards + firmware [ARM] Do not re-enumerate the bus but instead + just use the configuration from the + bootloader. This is currently used on + IXP2000 systems where the bus has to be + configured a certain way for adjunct CPUs. + noearly [X86] Don't do any early type 1 scanning. + This might help on some broken boards which + machine check when some devices' config space + is read. But various workarounds are disabled + and some IOMMU drivers will not work. + bfsort Sort PCI devices into breadth-first order. + This sorting is done to get a device + order compatible with older (<= 2.4) kernels. + nobfsort Don't sort PCI devices into breadth-first order. + cbiosize=nn[KMG] The fixed amount of bus space which is + reserved for the CardBus bridge's IO window. + The default value is 256 bytes. + cbmemsize=nn[KMG] The fixed amount of bus space which is + reserved for the CardBus bridge's memory + window. The default value is 64 megabytes. + resource_alignment= + Format: + [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...] + Specifies alignment and device to reassign + aligned memory resources. + If <order of align> is not specified, + PAGE_SIZE is used as alignment. + PCI-PCI bridge can be specified, if resource + windows need to be expanded. + ecrc= Enable/disable PCIe ECRC (transaction layer + end-to-end CRC checking). + bios: Use BIOS/firmware settings. This is the + the default. + off: Turn ECRC off + on: Turn ECRC on. + + pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power + Management. + off Disable ASPM. + force Enable ASPM even on devices that claim not to support it. + WARNING: Forcing ASPM on may cause system lockups. + + pcie_ports= [PCIE] PCIe ports handling: + auto Ask the BIOS whether or not to use native PCIe services + associated with PCIe ports (PME, hot-plug, AER). Use + them only if that is allowed by the BIOS. + native Use native PCIe services associated with PCIe ports + unconditionally. + compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe + ports driver. + + pcie_pme= [PCIE,PM] Native PCIe PME signaling options: + nomsi Do not use MSI for native PCIe PME signaling (this makes + all PCIe root ports use INTx for all services). + + pcmv= [HW,PCMCIA] BadgePAD 4 + + pd. [PARIDE] + See Documentation/blockdev/paride.txt. + + pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at + boot time. + Format: { 0 | 1 } + See arch/parisc/kernel/pdc_chassis.c + + percpu_alloc= Select which percpu first chunk allocator to use. + Currently supported values are "embed" and "page". + Archs may support subset or none of the selections. + See comments in mm/percpu.c for details on each + allocator. This parameter is primarily for debugging + and performance comparison. + + pf. [PARIDE] + See Documentation/blockdev/paride.txt. + + pg. [PARIDE] + See Documentation/blockdev/paride.txt. + + pirq= [SMP,APIC] Manual mp-table setup + See Documentation/x86/i386/IO-APIC.txt. + + plip= [PPT,NET] Parallel port network link + Format: { parport<nr> | timid | 0 } + See also Documentation/parport.txt. + + pmtmr= [X86] Manual setup of pmtmr I/O Port. + Override pmtimer IOPort with a hex value. + e.g. pmtmr=0x508 + + pnp.debug [PNP] + Enable PNP debug messages. This depends on the + CONFIG_PNP_DEBUG_MESSAGES option. + + pnpacpi= [ACPI] + { off } + + pnpbios= [ISAPNP] + { on | off | curr | res | no-curr | no-res } + + pnp_reserve_irq= + [ISAPNP] Exclude IRQs for the autoconfiguration + + pnp_reserve_dma= + [ISAPNP] Exclude DMAs for the autoconfiguration + + pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration + Ranges are in pairs (I/O port base and size). + + pnp_reserve_mem= + [ISAPNP] Exclude memory regions for the + autoconfiguration. + Ranges are in pairs (memory base and size). + + ports= [IP_VS_FTP] IPVS ftp helper module + Default is 21. + Up to 8 (IP_VS_APP_MAX_PORTS) ports + may be specified. + Format: <port>,<port>.... + + print-fatal-signals= + [KNL] debug: print fatal signals + + If enabled, warn about various signal handling + related application anomalies: too many signals, + too many POSIX.1 timers, fatal signals causing a + coredump - etc. + + If you hit the warning due to signal overflow, + you might want to try "ulimit -i unlimited". + + default: off. + + printk.time= Show timing data prefixed to each printk message line + Format: <bool> (1/Y/y=enable, 0/N/n=disable) + + processor.max_cstate= [HW,ACPI] + Limit processor to maximum C-state + max_cstate=9 overrides any DMI blacklist limit. + + processor.nocst [HW,ACPI] + Ignore the _CST method to determine C-states, + instead using the legacy FADT method + + profile= [KNL] Enable kernel profiling via /proc/profile + Format: [schedule,]<number> + Param: "schedule" - profile schedule points. + Param: <number> - step/bucket size as a power of 2 for + statistical time based profiling. + Param: "sleep" - profile D-state sleeping (millisecs). + Requires CONFIG_SCHEDSTATS + Param: "kvm" - profile VM exits. + + prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk + before loading. + See Documentation/blockdev/ramdisk.txt. + + psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to + probe for; one of (bare|imps|exps|lifebook|any). + psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports + per second. + psmouse.resetafter= [HW,MOUSE] + Try to reset the device after so many bad packets + (0 = never). + psmouse.resolution= + [HW,MOUSE] Set desired mouse resolution, in dpi. + psmouse.smartscroll= + [HW,MOUSE] Controls Logitech smartscroll autorepeat. + 0 = disabled, 1 = enabled (default). + + pt. [PARIDE] + See Documentation/blockdev/paride.txt. + + pty.legacy_count= + [KNL] Number of legacy pty's. Overwrites compiled-in + default number. + + quiet [KNL] Disable most log messages + + r128= [HW,DRM] + + raid= [HW,RAID] + See Documentation/md.txt. + + ramdisk_blocksize= [RAM] + See Documentation/blockdev/ramdisk.txt. + + ramdisk_size= [RAM] Sizes of RAM disks in kilobytes + See Documentation/blockdev/ramdisk.txt. + + rcupdate.blimit= [KNL,BOOT] + Set maximum number of finished RCU callbacks to process + in one batch. + + rcupdate.qhimark= [KNL,BOOT] + Set threshold of queued + RCU callbacks over which batch limiting is disabled. + + rcupdate.qlowmark= [KNL,BOOT] + Set threshold of queued RCU callbacks below which + batch limiting is re-enabled. + + rdinit= [KNL] + Format: <full_path> + Run specified binary instead of /init from the ramdisk, + used for early userspace startup. See initrd. + + reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode + Format: <reboot_mode>[,<reboot_mode2>[,...]] + See arch/*/kernel/reboot.c or arch/*/kernel/process.c + + relax_domain_level= + [KNL, SMP] Set scheduler's default relax_domain_level. + See Documentation/cgroups/cpusets.txt. + + reserve= [KNL,BUGS] Force the kernel to ignore some iomem area + + reservetop= [X86-32] + Format: nn[KMG] + Reserves a hole at the top of the kernel virtual + address space. + + reset_devices [KNL] Force drivers to reset the underlying device + during initialization. + + resume= [SWSUSP] + Specify the partition device for software suspend + + resume_offset= [SWSUSP] + Specify the offset from the beginning of the partition + given by "resume=" at which the swap header is located, + in <PAGE_SIZE> units (needed only for swap files). + See Documentation/power/swsusp-and-swap-files.txt + + hibernate= [HIBERNATION] + noresume Don't check if there's a hibernation image + present during boot. + nocompress Don't compress/decompress hibernation images. + + retain_initrd [RAM] Keep initrd memory after extraction + + rhash_entries= [KNL,NET] + Set number of hash buckets for route cache + + riscom8= [HW,SERIAL] + Format: <io_board1>[,<io_board2>[,...<io_boardN>]] + + ro [KNL] Mount root device read-only on boot + + root= [KNL] Root filesystem + + rootdelay= [KNL] Delay (in seconds) to pause before attempting to + mount the root filesystem + + rootflags= [KNL] Set root filesystem mount option string + + rootfstype= [KNL] Set root filesystem type + + rootwait [KNL] Wait (indefinitely) for root device to show up. + Useful for devices that are detected asynchronously + (e.g. USB and MMC devices). + + rw [KNL] Mount root device read-write on boot + + S [KNL] Run init in single mode + + sa1100ir [NET] + See drivers/net/irda/sa1100_ir.c. + + sbni= [NET] Granch SBNI12 leased line adapter + + sched_debug [KNL] Enables verbose scheduler debug messages. + + security= [SECURITY] Choose a security module to enable at boot. + If this boot parameter is not specified, only the first + security module asking for security registration will be + loaded. An invalid security module name will be treated + as if no module has been chosen. + + selinux= [SELINUX] Disable or enable SELinux at boot time. + Format: { "0" | "1" } + See security/selinux/Kconfig help text. + 0 -- disable. + 1 -- enable. + Default value is set via kernel config option. + If enabled at boot time, /selinux/disable can be used + later to disable prior to initial policy load. + + apparmor= [APPARMOR] Disable or enable AppArmor at boot time + Format: { "0" | "1" } + See security/apparmor/Kconfig help text + 0 -- disable. + 1 -- enable. + Default value is set via kernel config option. + + serialnumber [BUGS=X86-32] + + shapers= [NET] + Maximal number of shapers. + + show_msr= [x86] show boot-time MSR settings + Format: { <integer> } + Show boot-time (BIOS-initialized) MSR settings. + The parameter means the number of CPUs to show, + for example 1 means boot CPU only. + + simeth= [IA-64] + simscsi= + + slram= [HW,MTD] + + slub_debug[=options[,slabs]] [MM, SLUB] + Enabling slub_debug allows one to determine the + culprit if slab objects become corrupted. Enabling + slub_debug can create guard zones around objects and + may poison objects when not in use. Also tracks the + last alloc / free. For more information see + Documentation/vm/slub.txt. + + slub_max_order= [MM, SLUB] + Determines the maximum allowed order for slabs. + A high setting may cause OOMs due to memory + fragmentation. For more information see + Documentation/vm/slub.txt. + + slub_min_objects= [MM, SLUB] + The minimum number of objects per slab. SLUB will + increase the slab order up to slub_max_order to + generate a sufficiently large slab able to contain + the number of objects indicated. The higher the number + of objects the smaller the overhead of tracking slabs + and the less frequently locks need to be acquired. + For more information see Documentation/vm/slub.txt. + + slub_min_order= [MM, SLUB] + Determines the mininum page order for slabs. Must be + lower than slub_max_order. + For more information see Documentation/vm/slub.txt. + + slub_nomerge [MM, SLUB] + Disable merging of slabs with similar size. May be + necessary if there is some reason to distinguish + allocs to different slabs. Debug options disable + merging on their own. + For more information see Documentation/vm/slub.txt. + + smart2= [HW] + Format: <io1>[,<io2>[,...,<io8>]] + + smp-alt-once [X86-32,SMP] On a hotplug CPU system, only + attempt to substitute SMP alternatives once at boot. + + smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices + smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port + smsc-ircc2.ircc_sir= [HW] SIR base I/O port + smsc-ircc2.ircc_fir= [HW] FIR base I/O port + smsc-ircc2.ircc_irq= [HW] IRQ line + smsc-ircc2.ircc_dma= [HW] DMA channel + smsc-ircc2.ircc_transceiver= [HW] Transceiver type: + 0: Toshiba Satellite 1800 (GP data pin select) + 1: Fast pin select (default) + 2: ATC IRMode + + softlockup_panic= + [KNL] Should the soft-lockup detector generate panics. + + sonypi.*= [HW] Sony Programmable I/O Control Device driver + See Documentation/sonypi.txt + + specialix= [HW,SERIAL] Specialix multi-serial port adapter + See Documentation/serial/specialix.txt. + + spia_io_base= [HW,MTD] + spia_fio_base= + spia_pedr= + spia_peddr= + + stacktrace [FTRACE] + Enabled the stack tracer on boot up. + + sti= [PARISC,HW] + Format: <num> + Set the STI (builtin display/keyboard on the HP-PARISC + machines) console (graphic card) which should be used + as the initial boot-console. + See also comment in drivers/video/console/sticore.c. + + sti_font= [HW] + See comment in drivers/video/console/sticore.c. + + stifb= [HW] + Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]] + + sunrpc.min_resvport= + sunrpc.max_resvport= + [NFS,SUNRPC] + SunRPC servers often require that client requests + originate from a privileged port (i.e. a port in the + range 0 < portnr < 1024). + An administrator who wishes to reserve some of these + ports for other uses may adjust the range that the + kernel's sunrpc client considers to be privileged + using these two parameters to set the minimum and + maximum port values. + + sunrpc.pool_mode= + [NFS] + Control how the NFS server code allocates CPUs to + service thread pools. Depending on how many NICs + you have and where their interrupts are bound, this + option will affect which CPUs will do NFS serving. + Note: this parameter cannot be changed while the + NFS server is running. + + auto the server chooses an appropriate mode + automatically using heuristics + global a single global pool contains all CPUs + percpu one pool for each CPU + pernode one pool for each NUMA node (equivalent + to global on non-NUMA machines) + + sunrpc.tcp_slot_table_entries= + sunrpc.udp_slot_table_entries= + [NFS,SUNRPC] + Sets the upper limit on the number of simultaneous + RPC calls that can be sent from the client to a + server. Increasing these values may allow you to + improve throughput, but will also increase the + amount of memory reserved for use by the client. + + swiotlb= [IA-64] Number of I/O TLB slabs + + switches= [HW,M68k] + + sysrq_always_enabled + [KNL] + Ignore sysrq setting - this boot parameter will + neutralize any effect of /proc/sys/kernel/sysrq. + Useful for debugging. + + tdfx= [HW,DRM] + + test_suspend= [SUSPEND] + Specify "mem" (for Suspend-to-RAM) or "standby" (for + standby suspend) as the system sleep state to briefly + enter during system startup. The system is woken from + this state using a wakeup-capable RTC alarm. + + thash_entries= [KNL,NET] + Set number of hash buckets for TCP connection + + thermal.act= [HW,ACPI] + -1: disable all active trip points in all thermal zones + <degrees C>: override all lowest active trip points + + thermal.crt= [HW,ACPI] + -1: disable all critical trip points in all thermal zones + <degrees C>: override all critical trip points + + thermal.nocrt= [HW,ACPI] + Set to disable actions on ACPI thermal zone + critical and hot trip points. + + thermal.off= [HW,ACPI] + 1: disable ACPI thermal control + + thermal.psv= [HW,ACPI] + -1: disable all passive trip points + <degrees C>: override all passive trip points to this + value + + thermal.tzp= [HW,ACPI] + Specify global default ACPI thermal zone polling rate + <deci-seconds>: poll all this frequency + 0: no polling (default) + + topology= [S390] + Format: {off | on} + Specify if the kernel should make use of the cpu + topology informations if the hardware supports these. + The scheduler will make use of these informations and + e.g. base its process migration decisions on it. + Default is off. + + tp720= [HW,PS2] + + tpm_suspend_pcr=[HW,TPM] + Format: integer pcr id + Specify that at suspend time, the tpm driver + should extend the specified pcr with zeros, + as a workaround for some chips which fail to + flush the last written pcr on TPM_SaveState. + This will guarantee that all the other pcrs + are saved. + + trace_buf_size=nn[KMG] + [FTRACE] will set tracing buffer size. + + trace_event=[event-list] + [FTRACE] Set and start specified trace events in order + to facilitate early boot debugging. + See also Documentation/trace/events.txt + + tsc= Disable clocksource-must-verify flag for TSC. + Format: <string> + [x86] reliable: mark tsc clocksource as reliable, this + disables clocksource verification at runtime. + Used to enable high-resolution timer mode on older + hardware, and in virtualized environment. + + turbografx.map[2|3]= [HW,JOY] + TurboGraFX parallel port interface + Format: + <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7> + See also Documentation/input/joystick-parport.txt + + uhash_entries= [KNL,NET] + Set number of hash buckets for UDP/UDP-Lite connections + + uhci-hcd.ignore_oc= + [USB] Ignore overcurrent events (default N). + Some badly-designed motherboards generate lots of + bogus events, for ports that aren't wired to + anything. Set this parameter to avoid log spamming. + Note that genuine overcurrent events won't be + reported either. + + unknown_nmi_panic + [X86] + Set unknown_nmi_panic=1 early on boot. + + usbcore.autosuspend= + [USB] The autosuspend time delay (in seconds) used + for newly-detected USB devices (default 2). This + is the time required before an idle device will be + autosuspended. Devices for which the delay is set + to a negative value won't be autosuspended at all. + + usbcore.usbfs_snoop= + [USB] Set to log all usbfs traffic (default 0 = off). + + usbcore.blinkenlights= + [USB] Set to cycle leds on hubs (default 0 = off). + + usbcore.old_scheme_first= + [USB] Start with the old device initialization + scheme (default 0 = off). + + usbcore.use_both_schemes= + [USB] Try the other device initialization scheme + if the first one fails (default 1 = enabled). + + usbcore.initial_descriptor_timeout= + [USB] Specifies timeout for the initial 64-byte + USB_REQ_GET_DESCRIPTOR request in milliseconds + (default 5000 = 5.0 seconds). + + usbhid.mousepoll= + [USBHID] The interval which mice are to be polled at. + + usb-storage.delay_use= + [UMS] The delay in seconds before a new device is + scanned for Logical Units (default 5). + + usb-storage.quirks= + [UMS] A list of quirks entries to supplement or + override the built-in unusual_devs list. List + entries are separated by commas. Each entry has + the form VID:PID:Flags where VID and PID are Vendor + and Product ID values (4-digit hex numbers) and + Flags is a set of characters, each corresponding + to a common usb-storage quirk flag as follows: + a = SANE_SENSE (collect more than 18 bytes + of sense data); + b = BAD_SENSE (don't collect more than 18 + bytes of sense data); + c = FIX_CAPACITY (decrease the reported + device capacity by one sector); + h = CAPACITY_HEURISTICS (decrease the + reported device capacity by one + sector if the number is odd); + i = IGNORE_DEVICE (don't bind to this + device); + l = NOT_LOCKABLE (don't try to lock and + unlock ejectable media); + m = MAX_SECTORS_64 (don't transfer more + than 64 sectors = 32 KB at a time); + o = CAPACITY_OK (accept the capacity + reported by the device); + r = IGNORE_RESIDUE (the device reports + bogus residue values); + s = SINGLE_LUN (the device has only one + Logical Unit); + w = NO_WP_DETECT (don't test whether the + medium is write-protected). + Example: quirks=0419:aaf5:rl,0421:0433:rc + + userpte= + [X86] Flags controlling user PTE allocations. + + nohigh = do not allocate PTE pages in + HIGHMEM regardless of setting + of CONFIG_HIGHPTE. + + vdso= [X86,SH] + vdso=2: enable compat VDSO (default with COMPAT_VDSO) + vdso=1: enable VDSO (default) + vdso=0: disable VDSO mapping + + vdso32= [X86] + vdso32=2: enable compat VDSO (default with COMPAT_VDSO) + vdso32=1: enable 32-bit VDSO (default) + vdso32=0: disable 32-bit VDSO mapping + + vector= [IA-64,SMP] + vector=percpu: enable percpu vector domain + + video= [FB] Frame buffer configuration + See Documentation/fb/modedb.txt. + + vga= [BOOT,X86-32] Select a particular video mode + See Documentation/x86/boot.txt and + Documentation/svga.txt. + Use vga=ask for menu. + This is actually a boot loader parameter; the value is + passed to the kernel using a special protocol. + + vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact + size of <nn>. This can be used to increase the + minimum size (128MB on x86). It can also be used to + decrease the size and leave more room for directly + mapped kernel RAM. + + vmhalt= [KNL,S390] Perform z/VM CP command after system halt. + Format: <command> + + vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic. + Format: <command> + + vmpoff= [KNL,S390] Perform z/VM CP command after power off. + Format: <command> + + vt.cur_default= [VT] Default cursor shape. + Format: 0xCCBBAA, where AA, BB, and CC are the same as + the parameters of the <Esc>[?A;B;Cc escape sequence; + see VGA-softcursor.txt. Default: 2 = underline. + + vt.default_blu= [VT] + Format: <blue0>,<blue1>,<blue2>,...,<blue15> + Change the default blue palette of the console. + This is a 16-member array composed of values + ranging from 0-255. + + vt.default_grn= [VT] + Format: <green0>,<green1>,<green2>,...,<green15> + Change the default green palette of the console. + This is a 16-member array composed of values + ranging from 0-255. + + vt.default_red= [VT] + Format: <red0>,<red1>,<red2>,...,<red15> + Change the default red palette of the console. + This is a 16-member array composed of values + ranging from 0-255. + + vt.default_utf8= + [VT] + Format=<0|1> + Set system-wide default UTF-8 mode for all tty's. + Default is 1, i.e. UTF-8 mode is enabled for all + newly opened terminals. + + vt.global_cursor_default= + [VT] + Format=<-1|0|1> + Set system-wide default for whether a cursor + is shown on new VTs. Default is -1, + i.e. cursors will be created by default unless + overridden by individual drivers. 0 will hide + cursors, 1 will display them. + + watchdog timers [HW,WDT] For information on watchdog timers, + see Documentation/watchdog/watchdog-parameters.txt + or other driver-specific files in the + Documentation/watchdog/ directory. + + x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of + default x2apic cluster mode on platforms + supporting x2apic. + + x86_mrst_timer= [X86-32,APBT] + Choose timer option for x86 Moorestown MID platform. + Two valid options are apbt timer only and lapic timer + plus one apbt timer for broadcast timer. + x86_mrst_timer=apbt_only | lapic_and_apbt + + xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. + xd_geo= See header of drivers/block/xd.c. + + xen_emul_unplug= [HW,X86,XEN] + Unplug Xen emulated devices + Format: [unplug0,][unplug1] + ide-disks -- unplug primary master IDE devices + aux-ide-disks -- unplug non-primary-master IDE devices + nics -- unplug network devices + all -- unplug all emulated devices (NICs and IDE disks) + unnecessary -- unplugging emulated devices is + unnecessary even if the host did not respond to + the unplug protocol + never -- do not unplug even if version check succeeds + + xirc2ps_cs= [NET,PCMCIA] + Format: + <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] + +______________________________________________________________________ + +TODO: + + Add more DRM drivers. |